In reply to HGTS:
The grangers /nickwax techwash stuff I'd essentially just traditional liquid soap, just like lux or basic hand soap but in liquid form.
This stuff isn't really very powerful as a detergent. Modern washing machine detergents are far more powerful.
A rep from rab told me to wash event garments in liquid washing machine detergent then techwash then rejuvenate the dwr with spray on tx-direct.
I've done this with event and it worked fine but I haven't done this with goretex.